Helical antennas are widely used and their operating characteristics are well known and understood in the art.
Some helical antennas are designed to remain permanently fixed in their normal operating configuration. On the other hand many applications require a deployable helical antenna that is movable between a collapsed position and extended position in the field. Examples of such deployable helical antennas are shown in U.S. Pat. Nos. 4,068,238, 3,646,566, 6,340,956, 5,977,932, 3,524,193.
Designing a collapsible helical antenna presents a challenge particularly with increasing wavelength. Challenges stem from the relationship between the overall helix diameter and cross-sectional diameter of the helical conductor or radiator and wavelength. In this regard it is known that the optimum overall diameter of the helical antenna is on the order of 0.3 times the central frequency wavelength. The optimum cross-sectional diameter of the helical conductor is on the order of 0.006 times the central frequency wavelength. At longer wavelengths the above relationships yield helix dimensions, which are too large for utilization of conventional helical antenna designs and deployment techniques.
There is a need for a collapsible helical antenna, which can be easily and quickly deployed in the field for reception of satellite signals on the ground.
There is a further need for a collapsible helical antenna, which is lightweight, easily carried on foot and quickly and efficiently deployed on the ground for reception of satellite signals.